Drilling and excavating apparatus are generally being used on construction sites to drill and excavate the stratum. The stratum generally can be divided into soft stratum and hard stratum depending on the areas. In the countries of Southeast Asia (Such as Malaysia) the stratum usually is a hard type bedrock. The hardness increases as the depth of the bedrock increases.
The drills used in the conventional drilling and excavating operation such as the one disclosed in R.O.C. patent publication No. 356896 entitled “Improved structure for drilling sleeve” has a drill with a helical periphery. It may be rotated continuously to sink into the stratum. When drilling deeper into the stratum, the stratum becomes harder and drilling speed is slower. Sometimes drilling and excavation operations cannot be continued and have to stop. To remedy this problem, R.O.C. patent publication No. 415320 entitled: “Improvement for the drill of air hammer” proposes to use a pneumatic approach to drive the drill to generate up and down vibrations, and the drill has a high hardness steel ball to enhance the strength of drilling and excavation. During drilling and excavating operations, the drill is driven by the pneumatic air hammer to generate up and down vibration to shatter the bedrock. The drill structure of having the high hardness steel ball on one end is expensive. When the drilling diameter increases, the diameters of the drill and the air hammer also have to increase. The costs are higher. Moreover, to strike the hard bedrock through the high hardness steel ball is easy to damage the drill.
In addition, during operations, the steel ball on the plane of the drill strikes the bedrock vertically. It is less likely to create large cracks on the bedrock, and the drill is easily damaged. With the steel ball on the drill plane hitting the bedrock vertically, the longitudinal striking force causes dusts to drift vertically. The rotating drill that sinks deeply into the stratum often generates a great amount of dusts which spread like water fall. This results in an undesirable working environment and is harmful to the workers.
Furthermore, in terms of operations, the conventional drilling and excavating process of the bedrock mainly includes two stages: the first stage is to hoist the drilling and excavating apparatus by a heavy machinery and to drill the bedrock until reaching a selected depth, then withdraw the drill; the second stage is to sink an earth excavation barrel by the heavy machinery to excavate the shattered rocks and soils, then proceed the next drilling and excavating operation for a deeper stratum. The shattering operation of the first stage and the excavating operation of the second stage are repeatedly performed. To use merely a single heavy machinery to perform the operations, the hoisting head has to be replaced repeatedly. It will result in higher costs, increased operation time and greater risks. The heavy machinery used on the construction site usually is bulky and heavy. Operation is tedious and risk on the construction site is higher.